Software-defined networking (SDN) is a network or paradigm of a new structure which came to the fore so as to fundamentally solve and renovate a structural problem in which a current Internet has by software, and is a concept including an application, a network operating system, hardware abstraction, a standardized interface, and hardware.
The SDN is a network structure in which a network control plane is separated from a physical network having a data transfer plane, and the separated control plane should necessarily have a plane capable of interacting with a data path on a network switch (hardware). One of the interaction or a communication mechanism is OpenFlow technology which is a standard interface for communication between a machine having the control plane and the network switch.
According to the SDN, the control plane which is called a controller is implemented in a separate machine instead of a switch or a router, and the machine may be a personal computer (PC) or a high-performance server.
Meanwhile, in third generation partnership project (3GPP) long term evolution (LTE), a station which is called an evolved nodeB (eNB) and a home eNB (HeNB) is defined. The eNB of them is a macro base station managing a general macro cell, and the HeNB is a femto base station managing a femtocell. That is, in the 3GPP, an environment in which a femto base station in which only a specific user can access besides a conventional macro base station is installed is considered. Here, the femto base station is an ultra micro mobile communication base station capable of accessing a mobile communication core network through a broadband network installed indoors such as home or office, and may be installed for the purpose of coverage increase, capacity increase, or provision of other differentiated service, etc. by a user or a business operator. A service coverage of the femto base station may be considered from at least about a few meters to a maximum macro service coverage. An example of the 3GPP LTE system as a communication system capable of being applied to a method of the present invention will be described.
FIG. 1 is a diagram for describing a principle of a conventional selective Internet protocol traffic offload (SIPTO) method, and FIG. 2 is a diagram for describing a problem according to a conventional SIPTO method. In FIGS. 1 and 2, reference numeral 10 represents a mobile communication terminal, and reference numerals 20 and 80 represent a femto base station and a macro base station managing a femtocell and a macro cell, respectively. Reference numeral 30 represents a router included in a local network, and reference numerals 40, 50, and 60 represent an Internet service provider (ISP), a mobile communication core network, for example, an evolved packet core (EPC) network, and a public data network or packet data network (PDN), respectively. Reference numerals 90 and 70 represent a local terminal and an external server connected to the router 30 of the local network and the PDN 60, respectively.
Meanwhile, in the 3GPP, standardization of two technologies which are called a local Internet protocol access (LIPA) and the SIPTO are in progress in order to solve overload of a network, and the LIPA is technology of processing data in the local network and the SIPTO is technology of selectively offloading a traffic according to destination of the traffic.
That is, as shown in FIG. 1, when the mobile communication terminal 10 transmits a specific traffic through the femto base station 20 or the macro base station 80, the SIPTO is called technology of transmitting a traffic passing through (a dotted line) the core network 50 by making a detour to the Internet 60 (through a dot dashed line) in order to reduce the overload of the core network 50.
As described above, according to the conventional SIPTO technology, since it is determined whether to offload the traffic by simply checking only a destination IP address, when the mobile communication terminal 10 deviates from a femtocell area and enters a macro cell area as shown in FIG. 2, a bearer (will be described hereinafter) should be reset. Consequently, data transmission may be inevitably delayed due to the resetting of the bearer, and when the data traffic is real-time data such as voice over IP (VOIP) voice data, inconvenience of use in which communication is disconnected may be generated due to the delay.
This work was supported by the ICT R&D program of MSIP/IITP, Republic of Korea. [13-911-05-001, Development of OpenFlow-based integrated management system for wired and wireless network]